LOS ANGELES (AP) -- Ren Bishop is one of many American drivers who texts, tweets and talks on her cellphone while she's behind the wheel -- and thinks it should be up to drivers to use their discretion when it comes to safety.

Though she admits thumbing her phone while driving is bad habit, the University of Missouri student says drivers "are mature enough to understand when it is appropriate and when it is not."

The National Transportation Safety Board disagrees, and it declared Tuesday that texting, emailing or chatting while driving is simply too dangerous to be allowed anywhere in the United States.

The board is urging all states to impose total bans except for emergencies following recent deadly crashes, including one in Missouri after a teenager sent or received 11 text messages within 11 minutes.

The unanimous recommendation from the five-member board would apply even to hands-free devices, a much stricter rule than any current state law.

NTSB chairwoman Deborah Hersman acknowledged that complying would involve changing what has become ingrained behavior for many Americans.

"We're not here to win a popularity contest," she said. "No email, no text, no update, no call is worth a human life."

Currently, 35 states and the District of Columbia ban texting while driving, while nine states and Washington, D.C., bar hand-held cellphone use. Thirty states ban all cellphone use for beginning drivers. But enforcement is generally not a high priority, and no states ban the use of hands-free devices for all drivers.

The immediate impetus for the NTSB's recommendation was last year's deadly pileup near Gray Summit, Mo., involving a 19-year-old pickup driver.

The board said the initial collision was caused by the teen's inattention while texting a friend about events of the previous night. The pickup, traveling 55 mph, hit the back of a tractor truck that had slowed for highway construction. The pickup was rear-ended by a school bus, and a second school bus rammed into the back of the first bus.

The pickup driver and a 15-year-old student on one of the buses were killed. Thirty-eight other people were injured.

In Missouri, texting is illegal for drivers 21 and under, which means the law would have applied to the 19-year-old. But the ban isn't aggressively enforced, NTSB member Robert Sumwalt said.

"Without the enforcement, the laws don't mean a whole lot," he said.

The law didn't apply to 22-year-old Bishop when she was pulled over Monday night for swerving while texting on the University of Missouri campus.

She blames a late night and schoolwork. The officer who stopped her told her to put her phone in the back seat and sent her home with a warning.

"I definitely have the bad habit of tweeting and driving, texting and driving, and updating my Facebook status," Bishop said. "I probably shouldn't but the technology makes it too easy."

About two out of 10 American drivers overall -- and half of drivers between 21 and 24 -- say they've thumbed messages or emailed from the driver's seat, according to a survey of more than 6,000 drivers by the National Highway Traffic Safety Administration.

At any given moment last year on America's streets and highways, nearly one in every 100 car drivers was texting, emailing, surfing the Web or otherwise using a hand-held electronic device, the safety administration said. Those activities were up 50 percent over the previous year.

NTSB investigators said they are seeing increasing texting, cellphone calls and other distracting behavior by drivers in accidents involving all kinds of transportation. It has become routine to immediately request the preservation of cellphone and texting records when an investigation begins.

In the past few years, the board has investigated a train collision in which the engineer was texting that killed 25 people in Chatsworth, Calif., a fatal accident near Philadelphia in which a tugboat pilot was talking on his cellphone and using a laptop computer, and a Northwest Airlines flight that sped more than 100 miles past its destination because both pilots were working on their laptops.

Last year, a driver was dialing his cellphone when his truck crossed a highway median near Munfordville, Ky., and collided with a 15-passenger van. Eleven people were killed.

While the NTSB doesn't have the power to impose restrictions, its recommendations carry significant weight with federal regulators, Congress and state lawmakers. But the board's decision to include hands-free cellphone use in its recommendation is likely to prove especially controversial.

No states currently ban hand-free use, although many studies show that it is often as unsafe as hand-held phone use because drivers' minds are on their conversations rather than what's happening on the road.

Bike messenger Jesus Santa Rosa, 24, says he's seen a lot of accidents that are caused by people using their cellphones while he maneuvers through the streets of downtown Los Angeles.

"I've seen people taking red lights while they're looking down at their cellphones," said Santa Rosa. "And a lot of people get hit -- bike messengers, pedestrians."

Santa Rosa says he was sideswiped by a woman who was exiting the freeway and charging onto downtown's surface streets at a high speed.

"This girl, when she stopped after she hit me, she was still talking on the phone as she got out of the car, like, telling someone she almost just killed someone," Santa Rosa said.

Still, he said a ban on hands-free devices would probably be going too far because "texting is more dangerous. They're not looking up."

Another NTSB recommendation Tuesday urges states to aggressively enforce current bans on text messaging and the use of cellphones and other portable electronic devices while driving.

The National Highway Traffic Safety Administration reported earlier this year that pilot projects in Syracuse, N.Y., and Hartford, Conn., produced significant reductions in distracted driving by combining stepped-up ticketing with high-profile public education campaigns.

Miami computer salesman Cully Waggoner, 50, agreed that texting is a danger to drivers but said enforcing bans is difficult. What may be more effective is harnessing technology to make technology safer, he said.

Perhaps phone manufacturers can be required to equip phones with a technology that disables texting and data packages if the phone is moving over a certain speed, Waggoner said.

"That would be the only way to get around to fixing anything: Go right to the technology that's being used," Waggoner said. Otherwise, "there's all kinds of laws on the books that people break every day, this would just be another one."

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Shaya Tayefe Mohajer can be reached at http://www.twitter.com/APShaya . Associated Press writer Joan Lowy in Washington contributed to this report and can be reached at http://www.twitter.com/AP--Joan--Lowy .